A five-day strike that workers on Southern Railway are "solidly supporting" will cause travel misery for hundreds of thousands of passengers.
As the strike starts, members of the Rail, Maritime and Transport (RMT) union have walked out. They're mounting picket lines outside stations in an escalating row over the role of conductors.
Southern's owner, Govia Thameslink Railway, apologised to passengers, describing the strike as "completely unjustified".
Some parts of Surrey and Sussex will have no trains at all because of the industrial action.
RMT general secretary Mick Cash said: "The strike action this morning is rock solid across the Southern Rail network as we fight to put rail safety before the profits of the failed Govia Thameslink operation.
"This action has been forced on us by the arrogance and inaction of Govia Thameslink and the Government, who have made it clear that they have no interest in resolving this dispute or in tackling the daily chaos on Southern."
Obvs passengers are taking to Twitter to discuss how the strikes are affecting them. And while they're not exactly happy about the situation, they're saying it's not much different to normal TBH.
Yeah, people are pretty frustrated with Southern Rail right now.
They don't really understand how the strikes are about safety.
An emergency timetable has been put in place, with Southern saying it will run 60% of services. And ironically, some people are saying this reduced service meant their train was on time for a change...
Of course, some tweeters are sticking up for the workers who are striking.
Hey, at least there's time for crosswords...